Americans who stayed at home before they were told to save lives, study finds

That’s the finding of a study published Monday in the journal “The Lancet: Infectious Diseases,” which used mobile phone data to track how people behaved between January 1 and April 20, some time before Widespread calls from state and local officials to stay home. .

Within four months of notification of Covid-19 in the U.S., the disease had spread to all states and more than 90% of all counties.

The study found that social distancing measures and the coronavirus slowdown were primarily due to changes in individual behavior and local regulations, noting that state and federal regulations were implemented too late or not implemented at all.

In the 25 counties evaluated in the study, people moved less than six to 29 days before state orders to stay home were implemented.

According to study authors Lauren Gardner, an associate professor in the department of civil and systems engineering at Johns Hopkins Whiting in 21 counties, cell phone data found that mobility slowed at the individual level even before the local orders to stay home. Ingeniery school.

Is using cell phone data a good way to track behavior?

They are a “good indicator of travel patterns because the person in question often carries the phones,” Flavio Toxvaerd, professor of economics at the Center for Interdisciplinary Research at the University of Cambridge, said in an email.

“In any case, the results match those found using other data, such as credit card transaction data,” said Toxvaerd, who was not involved in the study.

From late January to mid-April, the study found that people reduced their daily movements by varying amounts: in New York City, people reduced their normal activity by 35%; while people in Houston’s Harris County reduced their activity by 63% of what was typical.

The study found that it took nine to 12 days, on average, for the effects to begin to appear on infection rates, which is somewhat consistent with the virus’s 5-14 day incubation period.

Gardner’s team said the strong connection between social distancing and decreased transmission rates means that a return to normal mobility across the country creates a significant risk of increased infections, one that is unlikely to be apparent for up to three weeks. after people begin to resume their normalcy. exercise.

“In fact, the information here is key,” said Toxvaerd. “You can’t react to changes in infection risks if you don’t know what they are.”

“There are those for whom information may not change behavior,” he added. “For those people, we may have to provide incentives for desirable social distancing behavior, for example through fines and incentives to stay home.”

Some limitations

The study did not distinguish between low-risk trips, such as going to the park, and higher-risk trips, such as going to the grocery store. Because the data did not include sociodemographic information, the researchers were unable to isolate information on older adults, those with medical conditions and neglected communities, for whom social distancing may be more difficult.

“If no action was taken at the individual and local levels, and the social distancing behavior was delayed until the directives were implemented at the state level, COVID-19 could have circulated without mitigation for additional weeks in most places, which it would inevitably lead to more infections and deaths, “Gardner said in a statement.

“It is within the power of every US resident, even without government mandates, to help curb the spread of COVID-19,” he added.